Latex agglutination test for detecting antibodies to Treponema pallidum

We have developed an automated latex agglutination test for Treponema pallidum (TPLA) for measurement of the concentration of treponemal antibodies in syphilitic sera. The assay needs neither a complicated pretreatment of the sera nor special techniques. Intra- and interassay precision studies showed high reproducibility. Potentially interfering substances, such as bilirubin, hemoglobin, triglycerides, and rheumatoid factor, did not affect the results. The results obtained with the TPLA test showed a strong correlation with those from conventional methods. This test for antibodies to T. pallidum may be useful for the mass screening of syphilitic infections.

Latex agglutination test for detecting antibodies to Treponema pallidum

We have developed an automated latex agglutination test for Treponema pallidum (TPLA) for measurement of the concentration of treponemal antibodies in syphilitic sera. The assay needs neither a complicated pretreatment of the sera nor special techniques. Intra- and interassay precision studies showed high reproducibility. Potentially interfering substances, such as bilirubin, hemoglobin, triglycerides, and rheumatoid factor, did not affect the results. The results obtained with the TPLA test showed a strong correlation with those from conventional methods. This test for antibodies to T. pallidum may be useful for the mass screening of syphilitic infections.

Role of Hageman factor/kallikrein-kinin system in pseudomonal elastase-induced shock model

The role of the Hageman factor dependent pathway in pseudomonal elastase-induced shock was investigated in guinea pigs. Presence of a bradykinin B2 receptor antagonist [D-Arg0,Hyp3,Thi5,8,D-Phe7]-bradykinin (200 nM) in the circulation prevented shock caused by an intrajugular injection of pseudomonal elastase (0.8 mg/kg body weight). During the lethal shock caused by elastase (1.2 mg/kg), a significant consumption of components of the Hageman factor/kallikrein-kinin system was observed such as 45.7 +/- 2.20% consumption of Hageman factor, 100 +/- 0% of prekallikrein, and 85.1 +/- 2.50 of high-molecular-weight kininogen. More striking evidence for the participation of this system was demonstrated in depletion experiments with monospecific F(ab')2 antibodies against the components of the system. After depletion of any one of the components, guinea pigs exhibited unresponsiveness to the same lethal dose of pseudomonal elastase in regard to the cardio-respiratory alterations. In vitro, pseudomonal elastase (60 micrograms/ml) possessed a capacity to generate substantial amount of bradykinin in undiluted plasmas of humans (300.0 +/- 32.16 ng/ml) as well as guinea pigs (460.2 +/- 20.67 ng/ml) at 37 degrees C but not in those deficient in Hageman factor or prekallikrein. These results strongly suggested a pathological role of elastase in pseudomonal sepsis through activation of the Hageman factor dependent pathway.

MKK1 and MKK2, which encode Saccharomyces cerevisiae mitogen-activated protein kinase-kinase homologs, function in the pathway mediated by protein kinase C

The PKC1 gene of Saccharomyces cerevisiae encodes a homolog of mammalian protein kinase C that is required for normal growth and division of yeast cells. We report here the isolation of the yeast MKK1 and MKK2 (for mitogen-activated protein [MAP] kinase-kinase) genes which, when overexpressed, suppress the cell lysis defect of a temperature-sensitive pkc1 mutant. The MKK genes encode protein kinases most similar to the STE7 product of S. cerevisiae, the byr1 product of Schizosaccharomyces pombe, and vertebrate MAP kinase-kinases. Deletion of either MKK gene alone did not cause any apparent phenotypic defects, but deletion of both MKK1 and MKK2 resulted in a temperature-sensitive cell lysis defect that was suppressed by osmotic stabilizers. This phenotypic defect is similar to that associated with deletion of the BCK1 gene, which is thought to function in the pathway mediated by PCK1. The BCK1 gene also encodes a predicted protein kinase. Overexpression of MKK1 suppressed the growth defect caused by deletion of BCK1, whereas an activated allele of BCK1 (BCK1-20) did not suppress the defect of the mkk1 mkk2 double disruption. Furthermore, overexpression of MPK1, which encodes a protein kinase closely related to vertebrate MAP kinases, suppressed the defect of the mkk1 mkk2 double mutant. These results suggest that MKK1 and MKK2 function in a signal transduction pathway involving the protein kinases encoded by PKC1, BCK1, and MPK1. Genetic epistasis experiments indicated that the site of action for MKK1 and MKK2 is between BCK1 and MPK1.

A yeast mitogen-activated protein kinase homolog (Mpk1p) mediates signalling by protein kinase C

Mitogen-activated protein (MAP) kinases are activated in response to a variety of stimuli through a protein kinase cascade that results in their phosphorylation on tyrosine and threonine residues. The molecular nature of this cascade is just beginning to emerge. Here we report the isolation of a Saccharomyces cerevisiae gene encoding a functional analog of mammalian MAP kinases, designated MPK1 (for MAP kinase). The MPK1 gene was isolated as a dosage-dependent suppressor of the cell lysis defect associated with deletion of the BCK1 gene. The BCK1 gene is also predicted to encode a protein kinase which has been proposed to function downstream of the protein kinase C isozyme encoded by PKC1. The MPK1 gene possesses a 1.5-kb uninterrupted open reading frame predicted to encode a 53-kDa protein. The predicted Mpk1 protein (Mpk1p) shares 48 to 50% sequence identity with Xenopus MAP kinase and with the yeast mating pheromone response pathway components, Fus3p and Kss1p. Deletion of MPK1 resulted in a temperature-dependent cell lysis defect that was virtually indistinguishable from that resulting from deletion of BCK1, suggesting that the protein kinases encoded by these genes function in a common pathway. Expression of Xenopus MAP kinase suppressed the defect associated with loss of MPK1 but not the mating-related defects associated with loss of FUS3 or KSS1, indicating functional conservation between the former two protein kinases. Mutation of the presumptive phosphorylated tyrosine and threonine residues of Mpk1p individually to phenylalanine and alanine, respectively, severely impaired Mpk1p function. Additional epistasis experiments, and the overall architectural similarity between the PKC1-mediated pathway and the pheromone response pathway, suggest that Pkc1p regulates a protein kinase cascade in which Bck1p activates a pair of protein kinases, designated Mkk1p and Mkk2p (for MAP kinase-kinase), which in turn activate Mpk1p.

[Histopathologic study of anterior capsule opacification in pseudophakic eyes]

We performed posterior chamber lens implantation (IOL) in three monkey eyes. All pseudophakic eyes developed a ring-shaped opacity, appearing on the IOL optics along the anterior capsule incision line. Transmission electron microscopic study revealed that the anterior capsule opacification was composed of proliferated cellular and extracellular components between the anterior capsule and the IOL optics. The proliferated cells looked like fibroblasts, but they were connected by desmosomes and covered by basal lamina. These histologic findings represented morphological features of epithelial cells, probably lens epithelial cells. Extracellular components consisted of collagen fibers, microfibrils, and basal lamina-like materials.

A specific host factor binds at a cis-acting transcriptionally silent locus required for stability control of yeast plasmid pSR1

A cis-acting locus, Z, of plasmid pSR1 functions in stable maintenance of the plasmid in the native host, Zygosaccharomyces rouxii. The Z locus was shown to be located in a 482 bp sequence in the 5' upstream region of an open reading frame, P, by subcloning various DNA fragments in a plasmid replicating via the ARS1 sequence of the Saccharomyces cerevisiae chromosome. Northern analysis revealed that the Z region is not transcribed in either the native host Z. rouxii or the heterologous host S. cerevisiae. The Z region is protected from micrococcal nuclease attack in Z. rouxii but not in S. cerevisiae, its protection depending on the product of the S gene encoded by pSR1. Gel retardation assays suggested that a factor present in nuclear extracts of Z. rouxii cells, irrespective of the presence or absence of a resident pSR1 plasmid, binds to a 111 bp RsaI-SacII sequence in the Z region. These findings suggest that a host protein binds to the Z locus and that the S product interacts with this DNA-protein complex and stabilizes pSR1.

Microbial hydroxylation of (-)-eburnamonine by Mucor circinelloides and Streptomyces violens

(6R)-6-Hydroxy-, (6S)-6-hydroxy- and (18S)-18-hydroxyeburnamonines were obtained by microbial conversion of (-)-eburnamonine using Mucor circinelloides and Streptomyces violens. Their structures were determined by analyses of the mass, 1H- and 13C-NMR spectra. (-)-Eburnamonine and the three hydroxylated compounds showed cerebral protecting effects against potassium cyanide intoxication in mice.

NE-100, a novel sigma receptor ligand: in vivo tests

It has been suggested that sigma receptor antagonists may be useful as antipsychotic drugs. N, N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]-ethylamine monohydrochloride (NE-100) is a novel compound with high affinity for the sigma receptor (IC50 = 4.16 nM), but low affinity (IC50 > 10,000 nM) for D1, D2, 5-HT1A, 5-HT2 and phencyclidine (PCP) receptors. The head-weaving behavior induced by either (+)SKF10047 or PCP was dose-dependently antagonized by NE-100 with oral ED50 at 0.27 and 0.12 mg/kg, respectively. NE-100 did not affect dopamine agonists-induced stereotyped behavior and/or hyperactivity. NE-100 failed to induce catalepsy in rats. These findings indicate that NE-100 may have antipsychotic activity without the liability of motor side effects typical of neuroleptics.

A gene, SMP2, involved in plasmid maintenance and respiration in Saccharomyces cerevisiae encodes a highly charged protein

The smp2 mutant of Saccharomyces cerevisiae shows increased stability of the heterologous plasmid pSR1 and YRp plasmids. A DNA fragment bearing the SMP2 gene was cloned by its ability to complement the slow growth of the smp2 smp3 double mutant (smp3 is another mutation conferring increased stability of plasmid pSR1). The nucleotide sequence of SMP2 indicated that it encodes a highly charged 95 kDa protein. Disruption of the genomic SMP2 gene resulted in a respiration-deficient phenotype, although the cells retained mitochondrial DNA, and showed increased stability of pSR1 like the original smp2 mutant. The fact that the smp2 mutant is not always respiration deficient and shows increased pSR1 stability even in a rho0 strain lacking mitochondrial DNA suggested that the function of the Smp2 protein in plasmid maintenance is independent of respiration. The SMP2 locus was mapped at a site 71 cM from lys7 and 21 cM from ilv2/SMR1 on the right arm of chromosome XIII.

Effect of VA-045 on a closed head injury model in rats

The effect of VA-045, a novel apovincaminic acid derivative, was studied in a model of closed head injury (CHI) in rats. CHI was induced by dropping a 400 g weight through a tube from 70 cm above a steel helmet placed on the vertex. Intravenous administration of VA-045 and thyrotropin-releasing hormone (TRH) reduced both the duration of loss of righting reflex and the duration of disruption of spontaneous movement caused by CHI. VA-045, but not TRH attenuated the CHI-induced decreased step through latency (STL) on a passive avoidance task. Over the same time schedule, however, VA-045 did not attenuate the scopolamine-induced decreased STL. CHI-induced reduction of the amplitude of somatosensory evoked potentials (SEP) was recovered by VA-045 but not by TRH. These findings indicate that VA-045 may be useful for treating patients with CHI-induced disturbance in consciousness.

Functional analysis of Box II mutations in yeast site-specific recombinases Flp and R. Significance of amino acid conservation within the Int family and the yeast sub-family

The site-specific recombinases Flp and R from Saccharomyces cerevisiae and Zygosaccharomyces rouxii, respectively, are related proteins that share approximately 30% amino acid matches. They exhibit a common reaction mechanism that appears to be conserved within the larger Integrase family of site-specific recombinases. Two regions of the proteins, designated as Box I and Box II, harbor, in addition to amino acid conservation, a significantly high degree of nucleotide sequence homology within their coding segments. Box II also contains two amino acids, a histidine and an arginine, that are invariant throughout the Int family. We have performed functional analysis of Flp and R variants carrying point mutations within the Box II segment. Several positions within Box II can tolerate substitutions with no effect, or only modest effects on recombination. Alterations of the Int family residues, His305 and Arg308, in the R protein lead to the arrest of recombination at the strand cleavage or the strand exchange step. This is very similar to previously observed "step-arrest" phenotypes in Flp variants altered at these positions and has strong implications for the catalytic mechanism of recombination. Flp and R variants at His305 and His309 can be complemented in half-site strand transfer by a corresponding Tyr343 to phenylalanine variant. In contrast to Arg308 Flp variants, which are efficiently complemented in half-site strand transfer by Flp(Y343F), no strong complementation has been observed between Arg308 variants of R and R (Y343F).

[A case of multiple pulmonary metastases from duodenal cancer showing partial response using 5'-DFUR and a small dose of MMC]

A 77-year-old female with primary duodenal cancer had undergone pancreatoduodenectomy in May, 1989. Postoperative chemotherapy was done in combination with MMC (mitomycin C), lentinan and UFT (combined medicine of tegafur and uracil). In August, 1991, the patient complained of a cough and then was examined for multiple pulmonary metastases from duodenal cancer by chest X-ray and CT-scan. Then, she received 5'-DFUR (400-800 mg) and MMC (total 6 mg). Two months from the start of this therapy, the cough almost vanished and pulmonary lesions were diminished markedly. For about five months, this case corresponded to partial response (PR) according to the response criteria proposed by Koyama-Saitoh. The side effects of 5'-DFUR were diarrhea and anorexia. Therefore, we think that 5'-DFUR and a small dose of MMC yielded a partial response to multiple pulmonary metastases from duodenal cancer.

Automatic elimination of unnecessary bacterial sequences from yeast vectors

Most vectors for Saccharomyces cerevisiae are shuttle vectors which can be both propagated and selected in Escherichia coli. The DNA segments, however, which are required for propagation in E. coli are unnecessary and moreover toxic in S. cerevisiae. To delete these harmful DNA fragments from the vector after it is introduced into S. cerevisiae cells, we propose a specific gene conversion mechanism of a yeast plasmid, pSR1. Plasmid pSR1 has a pair of inverted repeats (IRs) that divides the plasmid molecule into two unique regions. Intramolecular recombination frequently occurs at a pair of specific recombination sites in IRs catalyzed by recombinase R, encoded by a pSR1 plasmid gene. This R-mediated recombination is often accompanied by gene conversion in IRs. Thus, a 2.1-kb pBR322 sequence for the E. coli host ligated into one of the IRs of a composite plasmid was automatically and effectively eliminated when the plasmid was introduced into S. cerevisiae cells.

Effects of pyridoxalated hemoglobin polyoxyethylene conjugate on diameter of rat mesenteric arterioles in situ

The effects of exchange transfusion (ET) with a modified hemoglobin (pyridoxalated hemoglobin polyoxyethylene conjugate, or PHP) on endothelium-dependent relaxation of microvasculature were examined in rat mesenteric arterioles using image-splitter television microscopy. To examine the endothelium-dependent relaxation, we applied acetylcholine (ACh) to arterioles preconstricted with norepinephrine (NE) and measured changes in arteriolar diameter. Topical application of NE (6 x 10(-8) to 6 x 10(-6)M) decreased the diameter of the arterioles dose-dependently to a mean of 45% (SE +/- 4%, n = 6) of the control. Topical application of ACh (7 x 10(-8) to 7 x 10(-6)M) increased the diameter of the arterioles preconstricted with NE in a dose-dependent manner and almost fully reversed the NE-induced decrease in diameter. ET with 6% PHP solution (30 ml/kg) induced an increase in the mean arterial blood pressure (MABP) from 117 +/- 5 to 132 +/- 4 mm Hg (n = 6, p < 0.05), with a concomitant decrease in diameter of arterioles, from 22.6 +/- 2.5 to 19.8 +/- 2.7 microns (p < 0.05). The MABP and arteriolar diameter gradually returned to the control level within 30 min after ET. Arteriolar changes in diameter in response to NE and ACh examined 30 min after ET were similar to those of the control. ET with 6% stroma-free hemoglobin (SFH; 30 ml/kg) did not alter arteriolar changes in diameter in response to NE and ACh. Results suggest that circulating PHP and SFH moieties do not interfere with endothelium-derived relaxing factor(s) induced by ACh in rat mesenteric microvasculatures in situ.

Functional analysis of box I mutations in yeast site-specific recombinases Flp and R: pairwise complementation with recombinase variants lacking the active-site tyrosine

The site-specific recombinases Flp and R from Saccharomyces cerevisiae and Zygosaccharomyces rouxii, respectively, are related proteins that belong to the yeast family of site-specific recombinases. They share approximately 30% amino acid matches and exhibit a common reaction mechanism that appears to be conserved within the larger integrase family of site-specific recombinases. Two regions of the proteins, designated box I and box II, also harbor a significantly high degree of homology at the nucleotide sequence level. We have analyzed the properties of Flp and R variants carrying point mutations within the box I segment in substrate-binding, DNA cleavage, and full-site and half-site strand transfer reactions. All mutations abolish or seriously diminish recombinase function either at the substrate-binding step or at the catalytic steps of strand cleavage or strand transfer. Of particular interest are mutations of Arg-191 of Flp and R, residues which correspond to one of the two invariant arginine residues of the integrase family. These variant proteins bind substrate with affinities comparable to those of the corresponding wild-type recombinases. Among the binding-competent variants, only Flp(R191K) is capable of efficient substrate cleavage in a full recombination target. However, this protein does not cleave a half recombination site and fails to complete strand exchange in a full site. Strikingly, the Arg-191 mutants of Flp and R can be rescued in half-site strand transfer reactions by a second point mutant of the corresponding recombinase that lacks its active-site tyrosine (Tyr-343). Similarly, Flp and R variants of Cys-189 and Flp variants at Asp-194 and Asp-199 can also be complemented by the corresponding Tyr-343-to-phenylalanine recombinase mutant.

Heparin adheres to the damaged arterial wall and inhibits its thrombogenicity

Heparin binds to thrombogenic extracellular matrices as well as to smooth muscle cells of the vascular wall in vitro. The inhibitory effects of heparin on thrombogenicity of the damaged arterial wall were examined in vivo using small mesenteric arteries of rats and a video recording system attached to a microscope. To induce thrombosis, we damaged the vessel wall over a short segment by compression and exposed the media to the blood stream. A platelet-rich thrombus enlarged gradually at the damaged site, occluded the vascular lumen for a short period, and then flowed away. Compression damage induced such thrombus formation several times. Heparin (500 units/ml) was given in three different ways: intravenous and intra-arterial administration (both 300 units/kg) and intraluminal application under stopped-flow conditions (less than 0.01 ml) for 1-2 minutes with subsequent draining out. Intravenous heparin significantly decreased both the total duration and the number of thrombotic occlusions, whereas intra-arterial heparin abolished thrombotic occlusion. Both routes of heparin administration similarly prolonged the blood coagulation time. Intraluminal application of heparin significantly inhibited subsequent thrombus formation after restoring the flow without changes in the blood coagulation time. After an intra-arterial administration or intraluminal application of fluorescein isothiocyanate-bound heparin, strong fluorescence was observed only at the damaged vascular segment. A heparin fraction with low affinity to antithrombin III or chondroitin sulfate A did not inhibit thrombosis. To clarify anticoagulant activity of vascular wall-bound heparin, damaged carotid arterial segments of rats were incubated (inside out) in platelet-poor plasma with thrombin, and fibrin clot formation around the segments with or without heparin binding was measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholinomimetic activity of minaprine is related to the amelioration of delayed neuronal death in gerbils

We attempted to determine if the cholinomimetic activity of the psychotropic drug minaprine was related to the amelioration of the delayed neuronal death induced by cerebral ischemia in Mongolian gerbils. Minaprine improved the passive avoidance deficit induced by cerebral ischemia, and the histopathological ischemic neuronal changes in the hippocampal CA1 neurons were diminished. These effects were completely inhibited by treatment with the cholinergic blocker scopolamine. Rectal temperature fell about 1.5 degrees C immediately after cerebral ischemia and hyperthermia occurred 30 and 60 min after recirculation. Minaprine had no effect on body temperature before or after ischemia. Physostigmine and tetrahydroaminoacridine (THA), drugs which stimulate the cholinergic system, improved passive avoidance deficits and prevented the delayed neuronal death. These effects of physostigmine and THA were completely inhibited by scopolamine. Pentobarbital and diazepam also improved the passive avoidance deficit and prevented the destruction of CA1 neurons. In contrast with minaprine, these effects of pentobarbital and diazepam were not inhibited by scopolamine. As the protective effect of minaprine against ischemia-induced delayed neuronal death is related to cholinomimetic activities, these events differ from those seen with pentobarbital and diazepam.

The efficiency of new leukocyte removal filters. CF-1 and CF-2

Two new leukocyte removal filters, Nipro CF-1 and CF-2 (Nipo Medical Industries, Osaka, Japan), were evaluated. These non-woven polyester filters, which are gravity flow devices that require no priming and no rinsing after use, were developed for preparing 400 ml of whole blood or red cell concentrates from 400 ml of whole blood. A flow cytometric technique was developed to measure extremely low white blood cell (WBC) counts. To evaluate the efficiency of these filters, leukocyte counts were measured by three techniques: 1) electronic, 2) visual, and 3) flow cytometry. Flow cytometric counting was done using a Coulter EPICS-C cytometer (Coulter Corp., Hialeah, FL). Nipro CF-1 removed 99.97 +/- 0.01% (mean +/- SD, n = 14) of leukocytes measured by flow cytometry, and CF-1 recovered 90.7 +/- 4.47% (n = 21) of red blood cells. After filtration through CF-2, more than a 6 log10 (> 99.9999%) depletion of WBCs was detected in six samples, a 6 log10 (99.9999%) depletion of WBCs was detected in two samples, a 5 log10 (99.999%) depletion was detected in five samples, and a 4 log10 (99.99%) depletion was detected in one sample. CF-1, in which size and priming volume was smaller than other commercial leukocyte removal filters, accomplished a 3 log10 reduction in WBC count, compared with other commercial filters. CF-2 achieved a 4-6 log10 depletion of WBCs assayed by flow cytometry.

Effects of nipradilol on the microvascular tone of rat mesentery: comparison with other beta-blockers and vasodilators

The effects of nipradilol, a nonselective beta-blocker with vasodilator activities, on the diameter of arterioles and venules were examined in rat mesentery in vivo and were compared with those of propranolol, atenolol, labetalol, nifedipine and nitroglycerin. Topical application of nipradilol (10(-7) M and 10(-6) M) dilated the arterioles significantly to 109 +/- 2% and 112 +/- 2% of control, respectively (mean +/- S.E.; n = 9; p < 0.01), without changes in blood pressure and pulse rate. The dilator effect was comparable to that of nifedipine and nitroglycerin. Propranolol constricted the arterioles (to 86 +/- 3% at 10(-7) M; n = 9; p < 0.01), but atenolol and labetalol had no significant effects. Nitroglycerin dilated venules significantly (to 108 +/- 2% at 10(-7) M; n = 6; p < 0.01) but other drugs showed no significant effects on the tone of venules. Unlike the other beta-blockers used in this study, nipradilol has dilator effects on arterioles as have nifedipine and nitroglycerin.

Half-site recombinations mediated by yeast site-specific recombinases Flp and R

The Flp recombinase of Saccharomyces cerevisae and the related R recombinase of Zygosaccharomyces rouxii can efficiently catalyze strand cleavage and strand exchange reactions in half recombination sites. A half-site consists of one recombinase binding element, a recombinase cleavage site on one strand and a 5' spacer hydroxyl group on the other that can initiate the strand exchange reaction. We have studied the various types of strand exchanges that half-sites can participate in. Reaction between a left half-site and a right half-site generates a full recombination site. Strand transfer between two left half-sites or between two right half-sites produces pseudo-full-sites. Strand transfer within a half-site results in a stem-loop or hairpin product. The half-site strand transfer reaction is fairly indifferent to the spacer sequence of the substrate per se and is less sensitive to variations in spacer lengths than a full-site recombination reaction. The optimal spacer length of eight to ten nucleotides observed for the Flp half-site reaction likely permits the most productive catalytic interactions between two Flp monomers bound to each of two partner half-sites. When reacted with a full-site, the half-site can give rise to a normal or reverse recombinant, corresponding to homologous or non-homologous alignments of the spacer sequences during substrate synapsis. The contrary recombination (resulting from non-homologous spacer alignment), whose level is low relative to normal recombination, is partly suppressed when the half-site spacer ends in a 5'-phosphate rather than a 5'-hydroxyl group. Thus, the early steps of recombination, namely synapsis and initial stand transfer, are not dependent on complete spacer homology between the two recombining substrates. The selection of properly aligned substrate partners must occur at the homology dependent branch migration step. In reactions containing a mixture of Flp and R half-sites, Flp and R catalyze strand transfer, almost exclusively, within or between their respective cognate substrates. However, under conditions where self-crosses are inhibited, strand exchange between a Flp half-site and an R half-site appears to be stimulated by a combination of R and Flp.

Sigma receptor modulation of the muscle relaxant action of eperisone

We examined the mechanism of the muscle relaxant action of eperisone, using Straub tail and binding studies. In vivo, eperisone (50 and 100 mg/kg i.p.) produced a dose-dependent inhibition of the Straub tail in mice and this inhibitory effect was significantly reversed by haloperidol (0.5 mg/kg i.p.). This drug in itself had no effect on the Straub tail. Sulpiride (50 mg/kg i.p.) failed to reverse the inhibitory effect of eperisone. In vitro, (+)-3-(3-[3H]hydroxyphenyl)-N-(1-propylpiperidine) ((+)-[3H]3-PPP) specific binding, in rat brain membrane, was prevented by eperisone and the IC50 value was 0.43 nM. The muscle relaxant action of eperisone may be modulated by sigma receptors.

Site-specific recombinase, R, encoded by yeast plasmid pSR1

The R gene product (R protein) of Zygosaccharomyces rouxii plasmid pSR1 catalyzes site-specific recombination within a 58 base-pair (bp) sequence present in the 959 bp inverted repeats of this plasmid. The R protein was produced in Escherichia coli and partially purified. The partially purified protein catalyzed site-specific recombination in vitro without the supply of an energy source. Recombination resulted in intramolecular inversion or deletion, depending on whether the orientations of the two recombination sites on the substrate plasmid were the same or opposite. Presumably, R protein is the only protein required for the recombination reaction. A circular DNA molecule appears to be a better substrate than a linear molecule in R-mediated in vitro intramolecular recombination. The R protein binds to a set of six 12 bp elements within the inverted repeats of pSR1. Two of these 12 bp elements are arranged in an inverted configuration with a 7 bp spacer in the 58 bp sequence. The R protein mediates strand cleavage in vitro at the junction between the 12 bp elements and the 7 bp spacer. The cleavage sites on the top and bottom strands are staggered and flanked by polypurine tracts that form part of the 12 bp elements.

Identification of candidate sequences that determine virulence in Coxsackievirus B4

We have previously shown that a major determinant of virulence for coxsackievirus B4 mapped to the 5' end of the viral genome. Comparison of the corresponding cDNA sequences of a virulent and a non-virulent virus has allowed the identification of candidate determinants of virulence in the 5' untranslated region and the capsid proteins VP1, VP2 and VP4. Thirteen nucleotide substitutions were observed in a region spanning 3298 nucleotides. Four mutations were detected in the non-coding region. Of the remaining nine mutations, four were silent while five resulted in amino acid substitutions in VP1, VP2 and VP4. The amino acid substitutions in the virulent virus were analyzed in relation to the three-dimensional structures of the capsid proteins of poliovirus. Two substitutions mapped to the amino termini of VP1 and VP4. Of the two substitutions observed in VP2, one mapped to the large loop that connects beta strand E with the radial helix on the back surface of the eight-stranded antiparallel beta barrel while the other mapped to beta strand G. One amino acid substitution in VP1 mapped to the loop connecting beta strands D and E at a site close to a major determinant of attenuation in poliovirus type 2.